ONE of a numerous and successful class of LMS 4-6-0 mixed traffic locomotives, No. 5241, is illustrated above. The first of the class, No. 5020, appeared in 1934 and since then no fewer than 452 have been built or ordered. These engines were designed for general utility work on all sections of the LMS, and they can haul lightweight expresses and heavy freight trains with equal competence. The later examples of the class, including No. 5241, differ in detail from the earlier engines.
Each engine has two cylinders, 18½ in by 28-in, placed outside the frames and driving the second coupled axle. Walschaerts valve gear and piston valves are fitted. The valve travel is 6½-in. The driving wheels are of 6 feet and the bogie wheels of 3 ft 3½-in diameter.
The boiler barrel has a length of 13 ft 10⅛-in and tapers from 4 ft 11 11/16-in to 5 ft 8½-in outside diameter. Top feed is provided and the later members of the class have domes. What appeared to be a squat dome in the earlier engines was the top feed cover. The Belpaire firebox is fitted with “pop” safety valves, the working pressure being 225 lb per square inch.
The tubes have 1,460, the firebox 171·3 and the superheater 307 square feet of heating surface, the total, including superheater, being 1938·3 square feet. The firegrate area is 28·65 square feet. Tractive effort, at 85 per cent boiler pressure, is 25,455 lb. The engine weighs, in working order, 70 tons 12 cwt, of which 53 tons 3 cwt are available for adhesion.
The six-wheeled tender accommodates 4,000 gallons of water and 9 tons of coal. The weight is 54 tons 13 cwt. Total weight of engine and tender, in working order, is 125 tons 5 cwt. Despite the relative smallness of their driving wheels, these locomotives have been timed at speeds in excess of ninety miles an hour on favourable gradients. Nos. 5278 and 5264 did exceptionally well on test runs made in April 1937 over the Midland Division of the LMS, between London (St. Pancras) and Manchester (Central).
This route abounds in heavy gradients. Between Derby and Manchester, a distance of 61·4 miles, it runs through the Peak District of Derbyshire and climbs to a height of nearly 1,000 feet above sea level, with long stretches as steep as 1 in 90. Yet No. 5278 hauled a load of 258 tons over this route at an average speed of 54·1 miles an hour from start to stop. In the southern section of the route, the 99·1 miles from Leicester to St. Pancras were covered by No. 5264, also hauling 258 tons, in 92½ minutes, at an average speed of 64·1 miles an hour.